1. Field of the Invention
The present invention relates to a body structure of a water-jet propulsion personal watercraft, and more particularly to a body structure of a personal watercraft having a closed rear space in a rear portion of the body.
2. Description of the Related Art
In recent years, water-jet propulsion personal watercraft have been widely used in leisure, sport, rescue activities, and the like. A typical personal watercraft includes an engine mounted in a space within the watercraft that is surrounded by a hull and a deck. The engine is configured to drive a water jet pump, which pressurizes and accelerates water sucked from a water intake generally provided on a bottom surface of the hull and ejects it rearward from an outlet port. As the resulting reaction, the personal watercraft is propelled forward.
The engine is mounted within an engine room located substantially at the center of the body of the personal watercraft. The water jet pump is equipped in a pump room in a rear portion of the body and located behind the engine room. The water jet pump is covered by a pump casing.
For the purpose of improved rigidity of the body, in some personal watercraft, a bulkhead is provided on a rear side of the engine room. In order to gain a buoyant force acting on the body, a closed space defined by the hull, the deck, and the bulkhead is formed behind the bulkhead, and contains a foam structure.
Within this closed rear space, various pipes, such as an exhaust pipe configured to discharge an exhaust gas from the engine outside the watercraft, a cooling water drawing pipe configured to draw water drawn from an inside of the water jet pump to the engine for use as cooling water to cool engine components, and a drain pipe configured to discharge water flowing into the engine room outside the watercraft, are provided, and these pipes form an intricate configuration.
Since the closed rear space has an intricate shape and contains various pipes as described above, a foam structure made of urethane that tends to be cured soon after being injected into the rear space. In this manner, a large amount of foam structure may be formed within the rear space with little effort.
However, the rear space is not completely sealed, and water sometimes flows into the rear space. In addition, since the rear space is substantially closed, the water remaining in the rear space is difficult to discharge. In a stand-up type personal watercraft, typically, an upper surface of a rear portion of the deck, i.e., an upper portion of the rear space forms a standing deck, and an opening for maintenance purpose that leads to an inside of the rear space is not provided. In this construction, the water remaining within the rear space is difficult to discharge.
The above described foam structure within the rear space, is formed by continuous air-bubbles and has water-absorbing ability. The water flowing into the rear space is absorbed by the foam structure, so that the buoyant force acting on the body is reduced. Further, the water absorbed in the foam structure is difficult to remove therefrom.